[PATCH v5] net: stmmac: fix maxmtu assignment to be within valid range

From: Kweh, Hock Leong
Date: Fri Jan 06 2017 - 20:27:08 EST


From: "Kweh, Hock Leong" <hock.leong.kweh@xxxxxxxxx>

There is no checking valid value of maxmtu when getting it from
device tree. This resolution added the checking condition to
ensure the assignment is made within a valid range.

Signed-off-by: Kweh, Hock Leong <hock.leong.kweh@xxxxxxxxx>
---
changelog v5:
* revert back that plat->maxmtu > ndev->max_mtu is a valid case
when ndev->max_mtu assignment is entering to the else statement
* add comment to enchance clarification

changelog v4:
* add print warning message when maxmtu > max_mtu as well
* add maxmtu = JUMBO_LEN into each *_default_data() at stmmac_pci.c

changelog v3:
* print the warning message only if maxmtu < min_mtu
* add maxmtu = JUMBO_LEN at stmmac_pci.c to follow stmmac_platform.c

changelog v2:
* correction of "devicetree" to "device tree" reported by Andy
* print warning message while maxmtu is not in valid range

drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 10 +++++++++-
drivers/net/ethernet/stmicro/stmmac/stmmac_pci.c | 6 ++++++
2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 92ac006..8e56dc4 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -3345,8 +3345,16 @@ int stmmac_dvr_probe(struct device *device,
ndev->max_mtu = JUMBO_LEN;
else
ndev->max_mtu = SKB_MAX_HEAD(NET_SKB_PAD + NET_IP_ALIGN);
- if (priv->plat->maxmtu < ndev->max_mtu)
+ /* Will not overwrite ndev->max_mtu if plat->maxmtu > ndev->max_mtu
+ * as well as plat->maxmtu < ndev->min_mtu which is a invalid range.
+ */
+ if ((priv->plat->maxmtu < ndev->max_mtu) &&
+ (priv->plat->maxmtu >= ndev->min_mtu))
ndev->max_mtu = priv->plat->maxmtu;
+ else if (priv->plat->maxmtu < ndev->min_mtu)
+ netdev_warn(priv->dev,
+ "%s: warning: maxmtu having invalid value (%d)\n",
+ __func__, priv->plat->maxmtu);

if (flow_ctrl)
priv->flow_ctrl = FLOW_AUTO; /* RX/TX pause on */
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_pci.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_pci.c
index a283177..3da4737 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_pci.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_pci.c
@@ -89,6 +89,9 @@ static void stmmac_default_data(struct plat_stmmacenet_data *plat)

/* Set default value for unicast filter entries */
plat->unicast_filter_entries = 1;
+
+ /* Set the maxmtu to a default of JUMBO_LEN */
+ plat->maxmtu = JUMBO_LEN;
}

static int quark_default_data(struct plat_stmmacenet_data *plat,
@@ -126,6 +129,9 @@ static int quark_default_data(struct plat_stmmacenet_data *plat,
/* Set default value for unicast filter entries */
plat->unicast_filter_entries = 1;

+ /* Set the maxmtu to a default of JUMBO_LEN */
+ plat->maxmtu = JUMBO_LEN;
+
return 0;
}

--
1.7.9.5